With the exhaust pipes temporarily in place, the plans call for 2 springs to attach to the firewall to support the pipes. But I hate drilling into stainless, and it would be just another couple of holes in the firewall.
So I decided to support the springs with an Adel clamp and a couple of smaller clamps, attached to the engine mount (photos below).
Lower exhaust pipes with springs, up to Adel clamp.
